Does anybody know how or if one can use siunitx V3 on Overleaf? It seems that Overleaf only has TeX Live 2020 which does not include the newest siunitx.
Is there any way of getting around that?
Overleaf only update after extensive testing. As such, as for any newer package, you'll need to add the file(s) to your project: in this case, you need a copy of (v3)
siunitx.sty, which you can get if you have an up-to-date local install or from the 'ready to install' zip on CTAN.